Sustainable packaging has now gone far beyond recycling. At Bio-Based World News we have reported many innovative breakthroughs such as packaging made from prawns and milk protein to achieve biodegradable packaging which perishes like orange peel. However, bio-based plastics used in injection food moulding is relatively unexplored territory. A new research project launched by the Dutch firm SFA Packaging is striving to achieve price-competitive packaging for this neglected area of the industry. The specific challenge of the new project is to produce thin walled transparent food wrap and bio-based plastics that are affordable and usually too adherent for this application.
"Production of an injection moulded food packaging demands different material characteristics."
“The interest in bio-based packaging decreases dramatically when people calculate what the switch to these materials would cost,” says Gerald Schennink, senior polymer scientist at Wageningen Food & Bio-based Research. This is also the experience of Niels L’Abée, director of SFA Packaging. “From clients we see no explicit willingness to pay extra, but at the same time everyone feels that there should be more environmentally friendly packaging available. This trend is even more evident among consumers.”
There are several bio-based plastics on the market, and most are suitable for film applications. Schennink believes, “Ideally, food packaging films must be strong and stiff. Polylactic acid (PLA), that is bio-based by origin, possesses these properties. Production of an injection moulded food packaging demands different material characteristics, however.”
How does it work?
Plastic material in the form of granules is melted until soft enough to be injected under pressure to fill a mould. The result is that the shape is exactly copied. Once the plastic moulding has cooled sufficiently to harden the injection mould opens releasing the part. The whole injection moulding process then repeats. Commercial available bio-based polyesters do not flow easily, and therefore one-to-one replacement of conventional plastic with bio-based plastic is difficult.
SFA Packaging’s project will focus on three innovations. The first involves the use of additives that improve the flow behaviour of bio-based plastics. Secondly the project partners will look into more sophisticated production procedures. A possible concept is not to close the mould entirely, but inject the plastic first and close the mould after some specific time. However, one of the biggest challenges will be creating a surround thin enough to reduce materials use without compromising on the functionality of the bio-plastic.
And thirdly, the packaging will need to perform as well as traditional ones. As well as keeping products clean, a container for cookies also keeps them fresh since hardly any water vapour will permeate through the packaging.
“We will not be able to achieve this with pol ylactic acid as its water vapour barrier is limited,” says L’Abée. “We will try to add an extra layer in the container that provides the required barrier properties”.
The final goal of the project is to develop profitably bio-based plastic packaging with around half the CO2 emissions in material and production per unit as compared to conventional plastics. It would also offer consumers the opportunity to select a ‘greener’ alternative. l’Abée: “Consumers don’t have that choice at this time as at present there is no alternative. In the future, the product may cost a little more, but the market will show whether consumers are willing to pay for environmental benefits.”
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